PRIMORDIAL CRANIUM OF THE CAT 389 



A cartilage, having the position and relations to the nasopala- 

 tine duct and to the anterior transverse lamina, such as presented 

 by the posterior lateral cartilage of Vesperugo and the lateral 

 process of the lamina transversalis anterior of FeUs, is of fre- 

 quent occurrence in the mammalian series. It stands as a sup- 

 port to the floor of the nose at the outer side of the entrance to 

 the nasopalatine duct and probably possesses, as Grosser says, a 

 great significance as a supplementary structure to the palate. 

 It is found in forms in which a nasopalatine cartilage (as here 

 defined) does not exist, notably in mammals having a very short 

 nasopalatine duct (Echidna) and also in forms where the naso- 

 palatine cartilage is present, in which cases it may be separate 

 from or united with the latter. 



In accordance with this view, the processus palatinus of 

 Echidna would be comparable with the posterior lateral cartilage 

 of Vesperugo, the lateral process of the lamina transversalis 

 anterior of Felis, and not with the cartilago ductus incisivi of 

 these forms. The primary relation of the nasopalatine cartilage 

 (cartilago ductus incisivi), on the other hand, appears to be 

 directly with the nasopalatine duct, as in the cat. There is some 

 evidence in the series of mammals of its correlation with the 

 presence of a long nasopalatine canal. Absence of a nasopala- 

 tine cartilage in the lower mammals and its independent origin 

 and late appearance in dsvelopment in the cat may be interpreted 

 as indicating that it is phylogenetically a recent acquisition to 

 the palatal skeleton, and also that its connection with the lateral 

 posterior cartilage may be regarded as secondary. 



Jacobson's cartilage, relatively short, arises independently, as 

 recorded by Schwink ('88) and as observed in the present study, 

 and remains ununited with other parts of the chondrocranium in 

 embryos of the cat up to 23.1 mm. In later stages, as Zucker- 

 kandl has observed, this cartilage has elongated and taken on 

 connections with the lamina transversalis posterior, thi'ough the 

 development of a slender paraseptal rod. Zuckerkandl believed 

 that Jacobson's cartilage represents the anterior half of a carti- 

 laginous ridge which is derived from the primitive floor of the 

 nose. This is in accord with Seydel's ('99) conception of the 



